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A novel Tenebrio molitor cadherin is a functional receptor for Bacillus thuringiensis Cry3Aa toxin

Jeff Fabrick1, Cris Oppert, Marcé D Lorenzen

  • 1United States Department of Agriculture Agricultural Research Service United States Arid-Land Agricultural Research Center, Maricopa, Arizona 85238, USA.

The Journal of Biological Chemistry
|May 7, 2009
PubMed

Insights

A newly identified cadherin protein in the Tenebrio molitor beetle acts as a receptor for Bacillus thuringiensis Cry3Aa toxin. This discovery highlights conserved mechanisms of Cry toxin action across insect orders.

Area of Science:

  • Entomology
  • Molecular Biology
  • Biochemistry

Background:

  • Bacillus thuringiensis (Bt) Cry toxins are potent biological insecticides.
  • Cadherin-like proteins function as Cry1A toxin receptors in Lepidoptera (moths and butterflies).

Purpose of the Study:

  • To identify and characterize a functional Cry3Aa toxin receptor in Coleoptera (beetles).
  • To investigate the role of this receptor in Cry3Aa toxicity and resistance.

Main Methods:

  • Cloning of the cadherin receptor TmCad1 from Tenebrio molitor larval midgut mRNA.
  • In vitro binding assays using a peptide from TmCad1 and Cry3Aa toxin.
  • RNA interference (RNAi) to knock down TmCad1 expression in T. molitor larvae.

Main Results:

  • The cloned protein, TmCad1, shares structural similarities with lepidopteran cadherin receptors.
  • A TmCad1 peptide specifically bound to Cry3Aa toxin and induced toxin oligomerization.
  • Knockdown of TmCad1 conferred significant resistance to Cry3Aa toxicity in T. molitor larvae.

Conclusions:

  • TmCad1 is a functional Cry3Aa toxin receptor in Tenebrio molitor.
  • This study reveals conserved mechanisms of Cry toxin action between Lepidoptera and Coleoptera.
  • TmCad1 represents a potential target for enhancing Bt-based pest control strategies.

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